Working for litigation attorneys is heck anyway! They are picky! I don't think it is you, it is the job/situation. I would stay as long as you could, if you want a well enough paying job like that? Just teach yourself that it's not you and your fault when the job becomes untenable?

I think the temp firms and everyone at the law firm knows the score, that it is a hard job to keep people in. That they asked you to stay on and threw you to that particular wolf, says a lot about how well they think of you, that you'd last longer than usual? I substituted for a litigation lawyer when his secretary was on vacation too, and he had me doing extra work for his law school professorship/classes he taught, etc.

Don't take it personally other than to know it's the other person who's impossible, not you who is slow or incompetent. I can't imagine anyone still using WordPerfect anymore; I didn't even think it existed! I loved that software but finally bit the bullet and forced myself to learn Word.